Arthritis is a public health challenge, affecting approximately 50 million people in the United States. Arthritis has been the most common cause of disability in the United States for the past 15 years and costs the U.S. economy an estimated $128 billion annually. Rheumatoid arthritis is a systemic disease characterized by inflammation of membranes that line joints and is accompanied by severe pain and joint damage. Osteoarthritis is the most common form of arthritis and is characterized by progressive breakdown of joint cartilage. Osteoarthritis often results in degenerative damage to joints of the hand. Endurance and resistance types of exercise have been shown to provide considerable disease-specific benefits for people with osteoarthritis and rheumatoid arthritis. Muscle strengthening exercises can help support the joints, improve function and/or joint pain, and facilitate maintaining bone strength without hurting the joints.
Users can improve strength, function, and/or joint pain in their hands by performing endurance and resistance types with a hand exercise device. An example hand exercise device may include a compressible surface such as a sphere made of a flexible material such as polyurethane, neoprene, silicone, or latex. A user holds the exercise device in their palm to apply a compressive force on the surface of the sphere. The sphere offers resistance to the compressive force applied by the user because of elastic properties of the material of the sphere. The exercise comprises repetitive application and removal of the compressive force on the surface of the sphere.
Another example of a hand exercise device may include compression springs instead of or in addition to a natural or engineered surface that offers resistance against a compressive force due to material elastic properties. One or more compression springs may be supported by a surface. A second surface may be supported by the compression springs. A user may apply a compressive force to perform hand exercises. The compression springs offer resistance to the applied compressive force. The exercise may comprise a specific number of repetitions of applying the compressive force on the surface. The user may disassemble the hand exercise device and replace the compression springs with another set of compression springs that offer more or less resistance to the applied compressive force.
Another example of a hand exercise device may include bands made of a polymer with elastomeric properties such as neoprene, silicone or latex supported by two support posts. One of the support posts is fixed, while the other support post may be moved by applying a tensile or pulling force on the support post. The movable support post transfers the applied pulling force to the elastomeric bands which may offer resistance to the applied pulling force. The exercise may comprise applying the pulling force on the movable support post for a specific number of repetitions.
Hand exercise devices that do not offer variable exercise resistance and precise finger flexion may not result in measurable improvement in joint strength and pain reduction. Hand exercise devices that include variable exercise resistance may have many parts and components that must be disassembled to replace the parts that offer exercise resistance. Such hand exercise devices may not encourage the user to exercise regularly. Disassembly of parts and replacement of exercise surfaces may also increase the cost of the hand exercise devices. Hand exercises that include applying a precise force using specific areas of the hand offers muscle flexion and can improve finger and hand strength while mitigating joint pain. Such exercises may be more beneficial than exercises that involve pushing or squeezing a compression surface because of the precision involved in applying a pushing force on a string, as opposed to an exercise surface.